The Enigma of the Spiral Waves takes its readers further into into the workings of the number system. Continuing to make use of Watkins and Tweed's innovative visual approach to communicating advanced mathematical ideas without any need for formulas, equations, x's or y's, the reader is introduced to the mystifying "Riemann zeros" and the notorious Riemann Hypothesis. It's eventually explained how the weird set of frequencies met at the end of Volume 1 have all of the mathematical "fingerprints" necessary to strongly suggest that they correspond to the vibrations of some kind of (unknown) "system". As Oxford mathematics professor Marcus du Sautoy has said, "We have all this evidence that the Riemann zeros are vibrations, but we don't know what's doing the vibrating."